Can biologically inspired patches yield a new age of transdermal delivery?

Abstract

Trauma issues of current transdermal drug-delivery patches for longterm use Transdermal drug delivery (TDD) is an attractive method, offering opportunities to address the low bioavailability of many oral drugs and to avoid the pain and inconvenience of intravenous drug administration [1]. In practice, the advantages of transdermal administration include high patient adherence, the ability to discontinue the treatment at any time, a controlled rate of drug delivery to the patient, a fixed plasma drug level and the elimination of the hepatic first-pass effect [2]. However, the requirements for TDD are challenging as the method of administration must avoid damage to the skin, especially in cases where use is long-term. Medicated adhesive patches have played a critical role in achieving TDD. There are few important criteria that should be satisfied by this approach: the patch should not cause skin irritation or sensitization, it should not leave behind a residue after being peeled off the skin and it should be possible to easily remove the patch without causing pain and damage. In addition, with increasing demands for preserving fragile skin (especially for elderly patients), moisture management, patient comfort and wearing time extension are also important factors in need of consideration. Currently, the majority of TDD patches do not succeed in meeting the aforementioned criteria. Therefore, the opportunity to fabricate less skin irritating and more biocompatible patches is potentially of great benefit [3]. Biologically inspired adhesives for TDD patches In recognition of a need for smarter adhesive technology for new medical patches, hierarchical micro/nano fibrillar structures, inspired from the feet of animals, such as beetles and geckos, have been developed and identified as potential candidates in solving the issues associated with traditional, medicated adhesive patches [4]. Since the discovery of the role of hierarchical gecko foot hairs [5], bioinspired dry adhesion has received a great deal of attention. ‘Dry’ adhesion is achieved by exploiting intermolecular surface forces such as van der Waals forces or electrostatic attractions between the finely structured feet and the substrate. Adhesion research has proved that the gecko-inspired directional-adhesion property is useful in a range of applications such as wall-climbing robots [6], advanced transfer printing [7] and transportation devices [8]. The technology has also been employed in the case of implantable sensor devices [9], as well as tissue adhesive [10] and other smart medical tapes. Compared with traditional adhesives, it has been reported that the dry adhesive skin patch can provide improved biocompatibility over a prolonged time period, presumably because the skin is better ventilated, as well as reduced contact of the skin with potentially irritating chemical species or adhesives. Moreover, the dry adhesive skin patch can be repeatedly administered and is less affected by environmental factors due to its adhesion largely originating Cheng-Chung Chang* *Graduate Institute of Biomedical Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung, 402, Taiwan, Republic of China Fax: +886 4 22852422 ccchang555@dragon.nchu.edu.tw Therapeutic Delivery Editorial